Synergy is interaction of two or more system elements that produce a combined effect greater than the sum of their separate effects. A system can be technical, biological or social. The additional effect or the difference that is created from such an interaction is called synergy or synergism. Sometimes synergy is expressed in a formula as “2+2=5” or “1+1=111”. Company mergers and acquisitions (M&A) can create synergy effect. Forecasting the expected synergy is especially important before company mergers, therefore this study focuses or types of synergy and their evaluation options. The Aim of the Study: to describe effects of synergy and its sources in processes of economy. Materials and Methods: examining written works and other sources using quantitative and qualitative approach. Results: Synergy can be created during M&A as well as in the process of clusterization. Conclusions: It is important to determine the types of synergy created and to perform their quantitative evaluation. Synergy can also be created in the process of clusterization for each of the parties involved.